The Antwerp and Fowler Belt.—Crosoby. 239 
drawn from specimens collected on the dump of Sterling mine. 
The shaded areas are wholly glassy quartz; but a part of that 
The included areas are wholly glassy quartz; but a part of that 
shown in figure 3 may not be vein quartz, although the main 
part of it certainly is, as indicated by the large size and dis- 
tinctly fragmental forms of the masses. In no instance does 
the chloritic rock itself, apart from the included quartz, appear 
to have been crushed or brecciated ; but the slickensides suggest, 
rather, a differential flowing which has brecciated the unyield- 
ing quartz veinlets. It is easy to see, in the light 
of these examples, that with slender veinlets, at least, a com- 
plete and seemingly original granulation of the quartz might 
result. Again, the secondary silica in a case of this kind does 
not necessarily assume wholly the form of veinlets, but it may 
have been developed in part as amygdules or pseudo-amygdules 
or as irregular segregations and replacements. Certain it is 
that a trap rock is, during the process of chloritization, a pro- 
lific source of free silica, which is unlikely in the case of a 
large dike to wholly escape, even into cracks in the rock itself, 
crystallizing in part in interstitial or disseminated forms. 
I have not observed the masses described by Prof. Smyth 
as showing gradation from the granite into the chloritic rock 
or greenstone; but not having read his paper before visiting 
the locality, | may have overlooked them. I venture the sug- 
gestion, however, that they may be inclusions of the granite 
in the basic dike, which have naturally shared the alteration of 
the latter and are by simple contact more or less stained or im- 
pregnated by the chloritic material. Of course, this might 
happen to the unbroken granite wall of the dike as well as to 
inclusions. As showing that granitic inclusions are not wholly 
wanting, I may add that my collection from the Sterling mine 
contains a mass of distinctly pegmatitic character, in which 
coarsely crystalline mica is a prominent feature, which I broke 
out of the soft, dark-green, chloritic rock. It does not, how- 
ever, show any important alteration, even the mica being still 
essentially intact. The sandstone on the opposite side of the 
dike, although of a distinctly permeable character, does not, so 
far as I have.observed, show any appreciable chloritic impreg- 
nation, notwithstanding the fact that it is at some points very 
deeply stained or impregnated, but not replaced, by the henr- 
tite. 
